Sheet metal cutting tool



Dec. 26, 1950 c. B. GRAY SHEET METAL CUTTING TOOL Filed Dec. 16, 1944 CHARLES B.G'RAY H. m I

Patented Dec. 26, 1950 UNITED STATES PATENT OFFICE SHEET METAL CUTTINGTOOL C ar es B. Gr y Sp n fiel Ba; Application December 16, 1944 Serial No. 568,509

9 Claims. (Cl. SU -241.)

This invention relates generally to a metalcut ting tool and more particularlyto certain im= movements in the construction of a portable, hand-held sheet metal cutting tool of: the nibbler type such as is disclosed in my prior United States Letters Patent Nos. 2,278,174 and 2,278,311, both granted on March 31, 2942.

Among the principal objects or the present in.- vention is to provide an improved construction of and mounting for the die whichcoacts with the reciprocating punch or coacting element of tie tool for cutting out of the Sheet metal or other material being out a successive series of chips or slugs to slit the work along a given line. It is essentialin tools of this character that the die be held firmly in position in order to provide for the most efficient cutting action for thetcol and in order to prevent premature wear of both the punch and the die. In order to insure the attainment of this desired objective, the present invention provides a form of die and mounting therefor which facilitates and insures suchseecurement of the die in operative position thatit is relatively immovable with respect to the reciprocating punch during all conditions ofnse of the tool, the mounting arrangement being such, however, that the diemay be readily removed for servicing, inspection or replacement without disturbine any other parts of the assembled nibbling tool.

A nirther and important object of the present invention is to provide the nibbling tool with: an improved construction of stripper Which serves the dual purpose of holding the cutting blade of the reciprocating punch firmly against its up= porting hacking and of stripping the stock I from the punch on the return stroke of the latter. In use of the nibbling tool it is frequently necessary to vary the adjustment of the stripper bothas respects its pressure against the cutting blade of the reciprocating punch and th extent ofits spacin from the die required to be varied de, pending upon the gauge and hardness of the sheet material to be cutby thenibbling tool and accordingly, is an object of the present invene tion to facilitate ready adjustment of the stripper in both of the foregoing respects.

In addition to the foregoing, it is an object of the present invention to provide arrangements; of a removable die and a readily adjustable stripper which are simple and inexpensive to manufacture and incorporate in the nibbling tool and which, at the same time, are of such design andconstruction as not to obscure from the :view ofthe operator the line along which the. work is to be ,cut.

Other objects and advantages of the inven tion willappear more fully hereinafter, it being In the said accompanying drawing, which i-llustrates a preferred construction of the parts ofthe present invention:

Figure 1 is a sideview showing partly inelevation and partly in vertical cross-section atool construction in accordancewith and embodying the principles of the present invention;

Figure 2 is a front view of the'operating head of the tool with the front cover thereof removed;

Figure 3 is a perspective view of the punchguiding and die-supportingmember showing the die secured inposition thereon;

Figure 4 is a side elevational view of th assembly shown in perspective in Figure 3;

Figure 5 is a bottom plan view of such-assembly;

Figure 6 is a sectional view taken on the line 6-6 of Figure 4; and

Figure 7 is a side elevational view of a keysuch as may beemploycd in cooperation with the motor shaft of the tool for'raising'or lowering the punch withrespect to its die. 'Referring-now to" the drawings, it will 'be'observed that the nibbling tool of the present in-.

vention is of a'form and construction adapted to be conveniently held in the hand of-the operator, the operating head of the tool, designated generally bythe reference numeral it, being secured in any suitable manner to the forward end 1 of the casing I! in which is housed an electric motor 2 for driving the main drive shaft I3 oi the tool through the intervention of suitable gears Hi.

The operating head ID of the tool is in all material respects similar to that shown in my prior Patent No. 2,278,311 aforesaid, and includes a channel-shaped guide idin which is adapted to be vertically reciprocated a supporting ncin- The reciprocating her It iorthe punch l1.

punch-supporting member Isis provided inits rear face with a transverse slot or groovein which is received a shoelfl fitted upon an cc centric l9, the said shoe being of a width-less than thewidth. of the-slotin wlich'it is fitted;

but of adepthsubstantiallyequalto said slot. Thus, when: the punchrsupporting-member t6 is properly fitted within its ehannel-shaped guide I5 and the eccentric shoe I8 is received within the transverse 451013111 groovein the backziaoe of the reciprocating member l6, rotation of the shaft l3 will cause the eccentric 59 to shift the shoe l8 laterally within the groove simultaneously as said shoe acts on the member Hi to effect vertical reciprocation of the latter.

Formed as an integral part of the channel-' shaped guide if: and extending downwardly from the lower extremity thereof is a channel shaped guide 23, this latter being provided with a frontally presenting channel in continuation of the channel formed in the upper guide 65. Formed in the forward face of the reciprocating punch-supporting member I3 isa vertically extending groove within which is fitted the squared shank of the punch or cutting tool ii. A clamping block 23 overlies the squared portion of the punch ii and is secured to the reciprocating member it by means of the bolts 24 to frictionally retain the punch in position against vertical displacement with respect to its supporting member It. As in the prior patented construction, in order to provide for maximum clamping action of the clamping block against the punch, the said block is preferably provided with an inner clamp shoe 25 which is pressed against the punch by means of the set screws 26.

Vertical adjustment of the punch l'l within its reciprocating support if; is effected by means of a screw 21 which is fitted Within an interiorly threaded bore 28 in the upper end of the reciprocating member it, this adjusting screw being arranged in vertical alinement with the punch and being adapted to engage the upper end thereof to serve not only as a fixed upper abutment for the punch, but also as a means for adjusting the punch vertically along its reciprocating axis, it being apparent that by adjusting the said screw 2? in one direction or another, a punch of given length may be positionally adjusted to present its cutting edge in more or less closely spaced relation to the cooperating die for the punch.

,Fitted within the channel-shaped lower guide 20 is a combination die-supporting and feedlimiting unit, designated generally by the reference numeral 29'and-shown most clearly in Figores 3 and 4. This unit Zilis in turn provided in its upper portion with a frontally presenting channel 33 which is adaptedto'be vertically alined with the punch-receiving groove in the reciprocating member l6 when the unit 29 is secured in position within its support 23, as shown in Figure l. The unit 29 is securely fixed in position within the said support 2d therefor by means of a pair of screws 3l-3l which are projected commonly through the base walls of the nested channeled members 2s and 23. It will thus be apparent that the channel 33 of the unit 29 serves as a fixed guide for the lower portion of the reciprocating punch ll during reciprocation thereof in unison with its reciprocating supporting member l3.

Extending downwardly from the channeled portion 33 of the unit 23 is apart 32 of reduced cross-section, this part 32 serving not only as abacking for the lower free end of the reciprocating punch, but also as a means for limiting the feed of the work relatively to the too]. As in the prior patented construction of my tool, this depending part 32 of the unit 29 is provided with a flat frontal face 33 which is in continuation of and isdisposed in the vertical plane of the rear face of the reciprocating punch ll. Also, the width of this backing 33 for the lower end of the punch is no greater than theeffective width of the lat- 1 ment with the die plate.

4 ter and, if desired, may be of less width than that of the punch. Further, the said punchbacking part 33 diminishes in width from front to rear thereof, particularly in the immediate vicinity of the feeding plane of the sheet metal to'be cut, in consequence of which it becomes possible to out a slot in the sheet material of a width equal to that of the punch and at the same time permit the tool as a whole to be more or less freely rotated in said slot to change the direction of the latter as circumstances may require. Thus, the tool is adapted to slit sheet material along sharply curved as well as straight lines of any independent length.

The construction of tool as described to this point is, as has already been indicated, quite similar in all material respects to that of my prior Patent No. 2,278,311 aforesaid. However, in the said prior patented construction, the main guide for the reciprocating punch-supporting member is shown formed as an integral forward extension of the front half of a two part casing for the motor and other parts immediately associated therewith. In the present instance, this main guide, herein designated by the reference numeral I5, is shown formed as an integral part of a circular plate 34 which is adapted to be secured, as by means of the bolts 35, to the flanged forward extremity of the motor housing ll. Of course, any suitable means or arrangement may be provided for mounting the operating head id in operative relation to the handheld motor unit without departing from the general principles of the present invention.

Referring now more particularly to Figures 3, 4 and 5, it will be noted that in the present construction, the punch-backing part 33 of the unit 29 is formed at its lower end with a pair of laterally spaced, forwardly projecting arms 36-36, these arms being formed as integral extensions of the depending part 32 of the guide member 29 and being separated from each other a distance equal to the width of the part 32. Also, the said arms 38-36 are each so offset laterally and forwardly of their support 32 as to provide the same with co-planar horizontally disposed fiat upper surfaces 37-31 and co-planar vertically disposed flat rear surfaces 38-38. The contiguous surfaces 3? and 38 of each arm 36 thus serve as a lateral seat for the die plate 39.

This'die plate 39, as most clearly appears in Figures 3, 4 and 5, is of generally U-shape in plan to provide a pair of rearwardly extending arms 43-40 which define therebetween a notch 4| of a width equal to that of the cutting blade of the punch I1 and the spacing between the die-supporting arms 36-33. ities of the arms 40-43 of the die plate 39 are each downwardly turned to form lugs 42-42 which respectively engage the rear surfaces 38-38 of the die-supporting arms, the die plate being secured in position by means of screws 43-43 which project upwardly through the diesupporting arms 35-33 into threaded engage- The notch 4| of the die plate is of such length and width that when the plate is secured in position as shown in Figures 3, 4 and 5, the three walls of the notch cooperate with the frontal face 33 of the depending part 32 of the combined punch guide and die-supporting member 29 to form a die opening 44 into which the lower extremity of the punch is adapted to project as it penetrates the sheet material overlying the die. It will be noted that the die opening 44 is of a shape closely corre- The rear extrem-l spending to the cross-sectional shape of the lower cutting extremity of the reciprocable punch I! and that the die opening is effectively maintained in exact alinement with the punch by means of the interlocking engagement of the lugs 42-42 of the die with the rear ends of the die-supportingarms 36-36, such lugs serving to prevent It will be observed that the overall dimensions of the die and its immediately associatedsupporting structure are sufficiently small topermit the same to be projected through arelatively small opening preliminarily provided in the sheet metal to be cut when it is desired to cutaxdesign or outline in the sheet metal without passing through an edge thereof. In this, connection, it will be noted further that the frontal edges of the die-supporting arms 3E--3B have their vertical edges chamfered or rounded, as at 46, such chamfering being continued upwardlythrough the die itself. Also, if desired, instead of forming the die-supporting members 36 36, as, freely extending elements, as shown in Figure 3,the forward endsbof said arms may be joined together by an integral hridgingmember, such construction being preferably obtainedby forming the die-support as a solid block extending forwardly of its support 32 and then cutting an opening therethrough of a shape and formsuitable to permit the free ejection of the punched outslugs, the opening so formedinthe diesupport being immediately below and in registry with the dieopening.

Operatively associated with the punch to strip the sheet metal therefrom upon each upward stroke of the punch is a stripper (see Figures 1 and 2). This stripper essentially consists of .a member 48 having a main central part 49 from which depends a co planar angularly related part 50, the lower extremity 5| ofwhich is adapted to engage and press the relativelythin blade portion' of the punch ['1 against theflat surface 33 ofthe feed-limiting member 32 of ,the combined punch guide and die-support 29. The upper end of t the part 49 of the stripper is provided withan integrally formed, laterally extending part ,52, which latter part also extends forwardly of the frontal surface of the portion-49 of the stripper.

The stripper is mounted upon a supporting plate 53 therefor which is in turnsecured, by means of the screws 54, to the body portionyZU of the operating head of the tool. Thissupporting plate 53 is provided to one sidethereof with a raised boss 55 having a vertically extending free edge 56 which serves as a side support for the central part 49 of the stripper. ThispartAB of the stripper is provided with a vertica11yelongated opening or slot 5'! extending transversely through the body, of the stripper, and a pivot pin 58 is projected therethrough and into the supporting boss 5, as at 59 (see Figured) to serve as a fulcrum about which the stripper may be pivotally adjusted to more or less tightly engage; the reduced blade portion of the cutting tool H. ,A screwtfl projects through theupper end of the stripper with its inner end engagingthe supporting plate 53, as at 5 l (seeFigure 2) it being 1ap parent that upon rotation of this ,screwafillin clockwise direction the strippenwill be,; cause,d to

rotate about its pivot pin 58- to thereby present its lower extremity 51 in firm engagement-with the cutting blade of the reciprocating tool.

The supporting plate 53 for the stripper is provided with a pair of frontally projecting lugs 6l.6l which rise outof the boss 55 as integral parts thereof. Operatively associated with these lugs is a vertically extending adjusting stem, 62, the upper end of which is threaded, as at 83, for

projection into the transversely extending part 52.

of the stripper. This adjusting stem 62 is further provided with a pair of vertically spaced integral collars 53, these collars being disposed respectively above and below the pair of lugs 6 t-H at the same time that the saidpairof lugs 6l-6l embrace therebetween that portion of the stem which extends between itsspaced collars. It will be apparent that by reason of this construction, rotation of the adjusting stem 62 in one direction or the other will eifect a correspondingvertical adjustment of the stripper to thereby provide for more or less space between the lower extremity of the upper surface of the die plate 39. Of course,

in effecting such vertical adjustment, the pivot pin 58 is first loosened, said pin being tightened onlyafter the proper adjustments of the stripper, both for distance of its lower edge above the die and for pressure engagement against the blade portion of the reciprocating punch, have been effected.

As in the construction of tool described in my previously issued Patent No. 2,278,311, the moving parts of the operating head of the tool are closedby a removable cover plate 65, which is secured to the channeled main guide member 15 by means of suitable screws 6%; projected into threaded apertures 61 suitably provided in said main guide member I5.

It will be apparent that in the tool as just described, the punch i! may be adjusted axially with respect to its die opening at by first loosening the clamping screws24 and 26 and then adjusting the upper adjusting screw 27 as desired. It will be understood, of course, that for proper adjustment of the punch, its upper end must be,

at 68, to receive a key 69 (see Figure '7) by meansv of which the main shaft of the tool may be rotated by hand to raise the punch to its upper limit of its throw. With the punch in such po-- sition, its adjustment as well as that of the. stripper may be readily effected, as hereinbefore described, to condition thetool for useon any gauge of stock to be out within the capacity of thetool.

It will be understood, of course, that the present construction of tool as hereinbefore described is susceptible of various changes and modifications which may bemade from time to time without departing from the general principles or real spirit of the present invention, and it is accordingly intended to claim the same broadly, as well as specifically, as indicated by the app-ended claims.

What is claimed as new and useful is:

1. In a motor-operated hand-held nibbling tool for slitting sheet material, areciprocable' punch, a relatively fixed guidefor said punch having a 7... punch-backing part terminating at its lower end in a die support, said punch-backing part having a fiat frontal face of a width not exceeding the width of the punch and of graduall reduced cross-section rearwardly of said face, said die support extending frontally of said punch-backing part and laterally to either side thereof and being provided with an opening therethrough, one edge of which is defined b a continuation of said flat face of the punch-backing part, and a die plate carried by said support, said die plate being notched to provide a pair of laterally spaced rearwardly extending arms which overlie the laterally extending portions of the die support, said arms having terminal extremities which interlock with the rear ends of the die support to prevent forward displacement of the die plate relatively to said punch-backing part.

2. In a motor-operated hand-held nibbling tool for slitting sheet material, a reciprocable punch, I.

relatively fixed guide for said punch having a punch-backing part terminating in a die support, said die support extending frontally of the punchbacking part and laterally to either side thereof, and a die plate disposed fiatwise upon the upper surface of said die support with its marginal front and side edges subtantiall flush with those of the said support, said die plate being provided with rearwardly disposed depending lugs respectively adapted to engage behind the rear ends of the die support to either side of the punchbacking part whereby to prevent forward displacement of the die plate with respect to said punchbacking part, said die support being provided with an opening therethrough, the rear edge of which is coincident with the frontal face of the punchbacking part to define the edge of a die opening and the said die plate being notched to provide a front edge for the die opening which is spaced forwardly of the punch-backing part to a distance substantially equal to the thickness of the cutting edge of the punch.

3. In a motor-operated hand-held nibbling tool for slitting sheet material, a reciprocable punch, a relatively fixed guide for said punch having a punch-backing part terminatin at its lower end in a die support, said punch-backing part havinga fiat frontal face of a width not exceeding the width of the punch and of gradually reduced moss-section rearwardly of said face, said die support extending frontally of said punch-backing part and laterally to either side thereof and being provided with an opening therethrough, one edge of which is defined by a continuation of said flat face of the punch-backing part, a die plate carried by said support, said die plate being notched to provide a pair of laterally spaced reai'tvardl extending arms which overlie the laterally extending portions of the die support and interlock with the rear ends of the latter to prevent forward displacement of the die plate relatively to said punch-backing part, and screw means extending upwardly through the die support and into the die plate for securing the same together.

4. In a motor-operated hand-held nibbling tool for slitting sheet material, a reciprocable punch, a relativel guide for said punch having a punch-backing part, the frontal face of which is fiat and of Width not exceeding that of the 7 punch, a stripper operatively associated with the punch and, having a part bearing against the frontal face of the punch adapted to restrain the latter from flexing outwardly and away from said punch-backing part, and screw means engageable' with said stripper for effecting verti-1 cal adjustment thereof upon rotation of saidmeans in one direction or the other.

5. In a motor-operated hand-held nibbling tool for slitting sheet material, a reciprocable punch, a relatively fixed guide for said punch having a punch-backing part, a stripper of generally bell crank form mounted upon a relatively fixed pivot, means extending through the upper arm of said stripper and engageable with a fixed part of the tool to swing the stripper about its pivot whereby to cause the lower arm of said stripper to engage and press the punch against its said punchbacking part, and axially fixed rotatable means engageable with the stripper to verticall adjust the same with relation to the plane of the sheet metal to be cut.

6. In a motor-operated hand-held nibbling tool for slitting sheet material, a reciprocable punch,- a relatively fixed guide for said punch having a punch-backing part, and a stripper assembly operatively associated with said reciprocable punch, said assembly including a relatively fixed plate providing a pivotal mounting for the stripper and a support for an axially fixed rotatable screw element threadedly engageable with the stripper for vertically adjusting the position of the latter upon rotation of the element in one direction orper for positionally adjusting the same about its pivot to vary, as desired, the pressure of the stripper against the punch.

8. In a motor-operated. hand-held nibbling tool for slitting sheet material, a reciprocable punch,

a relatively fixed guide for said punch having a' punch-backing part terminating in a die support, a die plate carried by said support, said die plate being centrally notched to provide a pair of laterally spaced arms defining therebetween a die opening, said arms being provided with terminal extremities which interlock with the rear of said die support to prevent displacement of the die plate forwardly of said punch-backing part, said arms being respectively in engagement with 0pposite sides of the said punch-backing part to prevent lateral displacement of the die plate with respect to said part.

9. In a motor-operated hand-held nibbling tool for slitting sheet material, a reciprocable punch, a relatively fixed guide for said punch having a punch-backing part terminating at its lower end in a die support, said punch-backing part having a flat frontal face of a width not exceeding the width of the punch and of gradually reduced cross-section rearwardly of said face, said die support extending frontally of said punch-backing part and laterally to either side thereof and being provided with an opening theretltrough, one edge of said opening being disposed in the vertical plane of th flat face of the punch-back ing part, and a die plate carried by said support,

said die plate being notched to provide a pair: of laterally spaced arms which embrace the said 9 punch-backing part and have integrally formed elements at their free ends which interlock with the die support to prevent planar disp1ac ment of the rear end of the die plate relatively to said reciprocating punch.

CHARLES B. GRAY.

REFERENCES CITED The following references are of record in the file of this patent:

Num" er 10 UNITED STATES PATENTS Name Date Sell Aug. 9, 1898 Webb Oct. 8, 1940 Gray Mar. 31, 1942 

